Implement safe_eval() in order to armour eval()

bzr revid: p_christ@hol.gr-20090909194325-hpn4cfhwehxg9dzk
2009-09-09 22:43:25 +03:00
parent 768ec7b320
commit 5f77353468
1 changed files with 63 additions and 0 deletions
@@ -0,0 +1,63 @@
+# -*- encoding: utf-8 -*-
+#
+# Copyright P. Christeas <p_christ@hol.gr> 2008,2009
+#
+#
+# WARNING: This program as such is intended to be used by professional
+# programmers who take the whole responsability of assessing all potential
+# consequences resulting from its eventual inadequacies and bugs
+# End users who are looking for a ready-to-use solution with commercial
+# garantees and support are strongly adviced to contract a Free Software
+# Service Company
+#
+# This program is Free Software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+###############################################################################
+
+__export_bis = {}
+
+def __init_ebis():
+	global __export_bis
+	
+	_evars = [ 'abs', 'all', 'any', 'basestring' , 'bin', 'bool', 
+		'chr', 'cmp','complex', 'dict', 'divmod', 'enumerate',
+		'float','format', 'frozenset', 'getattr', 'hasattr', 'hash',
+		'hex', 'id','int', 'iter', 'len', 'list', 'long', 'map', 'max',
+		'min','next', 'oct', 'ord','pow', 'range', 'reduce', 'repr',
+		'reversed', 'round', 'set', 'setattr', 'slice','sorted', 'str',
+		'sum', 'tuple','type', 'unichr','unicode', 'xrange',
+		'True','False', 'None', 'NotImplemented', 'Ellipsis', ]
+		
+	for v in _evars:
+		__export_bis[v] = __builtins__[v]
+	
+
+__init_ebis()
+
+
+def safe_eval(expr,sglobals,slocals = None):
+	""" A little safer version of eval().
+	    This one, will use fewer builtin functions, so that only
+	    arithmetic and logic expressions can really work """
+	
+	global __export_bis
+
+	if not sglobals.has_key('__builtins__'):
+		# we copy, because we wouldn't want successive calls to safe_eval
+		# to be able to alter the builtins.
+		sglobals['__builtins__'] = __export_bis.copy()
+		
+	return eval(expr,sglobals,slocals)
+	
+#eof